224 J. A. POLLOCK. 



area of surface, at the absolute temperature 0, is not 

 measured by the value of the surface tension at that tem- 

 perature, but by the value of the expression, s - Ods/dd, ? 

 being the surface tension. This matter has been empha- 

 sized, indeed, by some previous writers, but judging from 

 recent literature the fact is not yet fully appreciated. 



For dilute solutions the expression for the surface excess 

 of solute, per unit area of surface, at the absolute tem- 

 perature #, is thus, 



V - G d ( c _ Q ds \ 



" ~m~dc~\ dor 



the symbols being used with usual significations. 



The heat change associated with such adsorption is, under 

 isothermal conditions at the absolute temperature 0, 

 6 {ds/dO - dsjdd), 



per unit area of surface, where § is the surface tension of 

 the solvent, and s e that of the solution. 



